Rolled copper foil for graphene and preparation method thereof

Abstract

The invention relates to the technical field of copper foil processing, in particular to rolled copper foil for graphene and a preparation method thereof.The rolled copper foil for graphene comprises, by mass, 0.0001%-0.0009% of O, 99.99%-99.995% of Cu and the balance unavoidable impurities, compared with the prior art, the rolled copper foil for graphene is prepared through raw material selection and treatment, and the yield of the rolled copper foil for graphene is improved; the influence of defects caused by impurities on the surface of the copper foil is reduced; through temperature control in the smelting and casting process, the influence of too high or too low temperature on the quality of a copper foil casting blank is reduced, through cooperative control of atmosphere heating, hot rolling, annealing and cold rolling, the probability of surface defects in all stages is reduced, the surface roughness of the rolled copper foil is reduced, and the rolled copper foil with the large grain size is obtained; therefore, the purpose of cooperative control of low surface roughness, low defect rate and large grain size is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of copper foil processing, and in particular to a rolled copper foil for graphene and a preparation method thereof. Background Art

[0002] Rolled copper foil has good ductility, folding resistance, low surface profile, high density and conductivity, and is an important material for manufacturing shielding materials, flexible printed circuit boards (FPCs), and transparent conductive films (graphene). Graphene is a two-dimensional material composed of a single layer of carbon atoms arranged in a hexagonal honeycomb shape. It has extremely high strength, electrical conductivity and thermal conductivity, and has broad application prospects in the fields of electronics, information, energy, materials, and biomedicine.

[0003] Methods for preparing graphene include mechanical exfoliation, chemical vapor deposition (CVD), oxidation-reduction method, etc. Among them, graphene prepared by chemical vapor deposition with rolled copper foil as substrate has the advantages of large area, high quality, controllable number of layers and low cost. Since the graphene prepared by chemical vapor deposition mainly grows on the surface of rolled copper foil, the graphene morphology completely replicates the surface structure of copper foil, and the surface defects and grain boundaries of rolled copper foil promote the nucleation of graphene, which has an adverse effect on the deposition and growth of graphene. In order to obtain high-quality large-area single-layer graphene, the rolled copper foil is required to have good surface morphology, low defect density, and large grain size, which are difficult problems in the production process of rolled copper foil. Based on this, the present invention provides a method for preparing rolled copper foil for graphene, which realizes the purpose of coordinated control of low surface roughness, low defect rate and large grain size, thereby achieving the purpose of stable production of rolled copper foil for graphene. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present invention provides a rolled copper foil for graphene and a preparation method thereof, so as to solve the problems of unstable surface roughness, high defect rate and insufficient grain size in the prior art.

[0005] The first aspect of the present invention provides a rolled copper foil for graphene, which comprises the following components in mass percentage: O content 0.0001-0.0009%, Cu content 99.99-99.995%, and the remainder being unavoidable impurities.

[0006] Furthermore, the rolled copper foil for graphene has a thickness of 20-50 μm, an average grain size of 400-600 μm, and a surface roughness of 0.06-0.08 μm.

[0007] A second aspect of the present invention provides a method for preparing a rolled copper foil for graphene, the preparation method specifically comprising the following steps:

[0008] S1. Weigh high-purity electrolytic copper as raw material, and bake and heat the raw material to obtain a dry, water-free, and oil-free molten casting material;

[0009] S2, smelting the molten casting material obtained in step S1, covering it with charcoal and letting it stand after smelting, placing it in a holding furnace after standing, covering it with flake graphite, and then obtaining a rolled copper foil ingot by a vertical full continuous casting method;

[0010] S3, subjecting the rolled copper foil ingot obtained in step S2 to a heating treatment and a hot rolling treatment in sequence to obtain a hot-rolled strip;

[0011] S4, subjecting the hot-rolled strip obtained in step S3 to milling treatment and rough rolling treatment in sequence, and then placing the hot-rolled strip in a bell-type furnace for secondary heating treatment to obtain a rough-rolled strip;

[0012] S5, subjecting the rough-rolled strip obtained in step S4 to intermediate rolling, primary annealing, finishing rolling and secondary annealing in sequence, and then placing the strip in a bell furnace for three annealing treatments to obtain a finished rolled copper foil;

[0013] S6. The finished rolled copper foil obtained in step S5 is subjected to heating and heat preservation treatment to obtain a rolled copper foil for graphene.

[0014] In some embodiments, in step S1, the parameters of the baking and heating treatment are as follows: temperature is 150-220° C., and time is 10-15 min.

[0015] In some embodiments, in step S2, the smelting temperature is 1200-1250°C, and the vertical full continuous casting temperature is 1180-1220°C.

[0016] In some embodiments, in step S3, a heating treatment is performed in a walking beam furnace, and the parameters of the heating treatment are as follows: a temperature of 920-950° C., a reducing atmosphere, and an air-fuel ratio of the reducing atmosphere of 0.92-0.98.

[0017] In some embodiments, in step S3, the parameters of the hot rolling process are as follows: a total of 7 passes, and the deformation amount of the 5th pass is 35-38%.

[0018] In some embodiments, in step S4, the parameters of the rough rolling process are as follows: a total of 7 passes, and the roll roughness is 0.4 μm.

[0019] In some embodiments, in step S4, the parameters of the secondary heating treatment are as follows: temperature is 550-800° C., and time is 3-5 h.

[0020] In some embodiments, in step S5, the parameters of the intermediate rolling process are as follows: a total of 5 passes, with a total deformation of 75-85% per pass, and a roller roughness of 0.2 μm.

[0021] In some embodiments, in step S5, a primary annealing treatment is performed in an air cushion furnace, and the parameters of the primary annealing treatment are as follows: a temperature of 650-700° C. and a time of 15-25 s.

[0022] In some embodiments, in step S5, the parameters of the finishing rolling process are as follows: 2 passes in total, with a total deformation of 15-25% per pass, and a roller roughness of 0.1 μm.

[0023] In some embodiments, in step S5, the secondary annealing treatment is performed in a bell furnace, and the parameters of the secondary annealing treatment are as follows: temperature is 230-260° C., and time is 10-15 hours.

[0024] In some embodiments, in step S6, the parameters of the heating and heat preservation treatment are as follows: temperature is 1000-1050° C., and time is 20-50 min. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a microstructure diagram of the rolled copper foil for graphene prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0029] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0030] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0031] In the prior art, in order to obtain high-quality large-area single-layer graphene, the rolled copper foil is required to have good surface morphology, low defect density, and large grain size, which are difficult problems in the production process of rolled copper foil. Therefore, the present invention provides a method for preparing rolled copper foil for graphene, which achieves the purpose of coordinated control of low surface roughness, low defect rate and large grain size, thereby achieving the purpose of stable production of rolled copper foil for graphene. In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a rolled copper foil for graphene, which includes the following components in mass percentage: O content 0.0001-0.0009%, Cu content 99.99-99.995%, and the balance is unavoidable impurities. It can be seen that the present invention strictly controls the content of oxygen, mainly because: trace oxygen can be used as a detergent to help remove some harmful impurities from copper, such as arsenic (As), antimony (Sb), bismuth (Bi) and other elements, which may affect the conductivity and mechanical properties of copper, but once the oxygen content exceeds the trace value (0.0009%), the microstructure of copper may be affected, causing the material to become brittle, reducing its ductility and tensile properties. Therefore, the present invention combines the charcoal covering and standing process on the basis of controlling the oxygen content. During the smelting process, part of the oxide can float to the surface of the melt to form slag and be removed, while the other part of the residual oxide can be removed after floating through the standing process. Therefore, the present invention uses a combination of oxygen content and preparation process to play the role of oxygen while avoiding its adverse effects, thereby improving the performance of the final rolled copper foil.

[0032] By controlling the constituent elements of the rolled copper foil for graphene of the present invention and combining the corresponding preparation method, the rolled copper foil for graphene prepared by the present invention has a thickness of 20-50 μm, an average grain size of 400-600 μm, and a surface roughness of 0.06-0.08 μm.

[0033] A second aspect of the present invention provides a method for preparing a rolled copper foil for graphene, which specifically comprises the following steps:

[0034] S1. Weigh high-purity electrolytic copper as raw material, and bake and heat the raw material to obtain a dry, water-free, and oil-free molten casting material;

[0035] S2, smelting the molten casting material obtained in step S1, covering it with charcoal and letting it stand after smelting, placing it in a holding furnace after standing, covering it with flake graphite, and then obtaining a rolled copper foil ingot by a vertical full continuous casting method;

[0036] S3, subjecting the rolled copper foil ingot obtained in step S2 to a heating treatment and a hot rolling treatment in sequence to obtain a hot-rolled strip;

[0037] S4, subjecting the hot-rolled strip obtained in step S3 to milling treatment and rough rolling treatment in sequence, and then placing the hot-rolled strip in a bell-type furnace for secondary heating treatment to obtain a rough-rolled strip;

[0038] S5, subjecting the rough-rolled strip obtained in step S4 to intermediate rolling, primary annealing, finishing rolling and secondary annealing in sequence, and then placing the strip in a bell furnace for three annealing treatments to obtain a finished rolled copper foil;

[0039] S6. The finished rolled copper foil obtained in step S5 is subjected to heating and heat preservation treatment to obtain a rolled copper foil for graphene.

[0040] In the embodiments and comparative examples of the present invention, the sizes of the billets prepared by the same steps are consistent. For example, in different embodiments and comparative examples, the thickness of the rolled copper foil ingots is consistent, the thickness of the hot-rolled strip billets is consistent, the thickness of the rough-rolled strip billets is consistent, the thickness of the intermediate-rolled strip billets is consistent, and the thickness of the finished rolled copper foil is consistent.

[0041] The present invention reduces the influence of defects caused by impurities on the surface of copper foil by selecting and processing raw materials; reduces the influence of excessively high or low temperature on the quality of copper foil ingot by controlling the temperature during smelting and casting; reduces the probability of surface defects in each stage by coordinated control of heating atmosphere, hot rolling, annealing and cold rolling, reduces the surface roughness of rolled copper foil, obtains rolled copper foil with larger grain size, and thus achieves the purpose of coordinated control of low surface roughness, low defect rate and larger grain size.

[0042] Furthermore, in step S1, the parameters of the baking and heating treatment are as follows: temperature is 150-220°C, time is 10-15min. The present invention first bakes and heats the raw materials to remove surface water and oil, thereby reducing the gas content during the ingot casting process and improving the internal quality of the ingot.

[0043] Furthermore, in step S2, the smelting temperature is 1200-1250°C, and the vertical full continuous casting temperature is 1180-1220°C. The present invention adopts a method of covering with charcoal and standing after smelting, the purpose of which is to protect the smelted copper liquid from oxidation. Charcoal, as a reducing agent, can form a protective layer on the surface of the copper liquid to reduce oxidation caused by contact with air. The standing process helps to evenly distribute the temperature and further float and separate impurities, and further remove the oxides obtained by combining oxygen elements with trace impurities. The use of flake graphite covering is to continue to provide protection and prevent the copper liquid from being oxidized in a heated state; finally, the vertical full continuous casting method is used to obtain the rolled copper foil ingot, which can not only improve production efficiency, but also keep the thickness of the ingot uniform.

[0044] Further, in step S3, a heating treatment is carried out in a step furnace, and the parameters of the heating treatment are as follows: the temperature is 920-950°C, the atmosphere is a reducing atmosphere, and the air-fuel ratio of the reducing atmosphere is 0.92-0.98. The present invention can effectively eliminate the casting stress and internal heterogeneity inside the ingot by limiting the heating temperature to 920-950°C, which is beneficial to homogenizing the microstructure of the material and improving the overall performance; and after the heating treatment is carried out in a reducing atmosphere, the air-fuel ratio of the reducing atmosphere is further limited, mainly because the reducing atmosphere can prevent copper from oxidizing at high temperatures and avoid hydrogen embrittlement, and the use of a slightly excessive air-fuel ratio of fuel can ensure the strong reducing nature of the heating environment. Under this condition, any residual oxygen in the furnace will be quickly consumed, creating an almost oxygen-free environment, which is very beneficial to the protection of copper materials, avoiding oxidation and promoting the optimization of material properties. If the reducing atmosphere is too large, the ingot will be unevenly heated due to incomplete combustion, resulting in poor heating.

[0045] Further, in step S3, the parameters of the hot rolling treatment are as follows: a total of 7 passes, and the deformation of the 5th pass is 35-38%. It should be noted that in the present technical solution, the thickness of the hot-rolled strip after the hot rolling treatment is generally about 17 mm. On the basis of the above, the present technical solution further discloses the total number of passes and the deformation of the 5th pass (the most critical pass), mainly because: the hot rolling treatment of copper is a processing process that reduces the thickness, increases the width or obtains the desired shape by applying pressure to the material under heating state to make it pass through a pair of rotating rollers. This process is crucial to improving the mechanical properties, processing properties and applicability of subsequent processing of copper materials. The present invention adopts the hot rolling treatment with the above parameters. Compared with the prior art, by adopting 7 passes of step-by-step processing, the microstructure and mechanical properties of the material can be more finely controlled, while reducing work hardening and ensuring the machinability of the material. The deformation amount of the 5th pass is further limited, mainly based on the understanding of material properties and the consideration of the specifications and performance requirements of the final product. The larger deformation amount of this pass can make the stress state of the strip compressive stress and more effectively weld the tiny defects in the ingot, thereby further improving the internal quality of the strip. Based on this, the inventor adopts the above hot rolling parameters.

[0046] Furthermore, in step S4, the parameters of the rough rolling process are as follows: a total of 7 passes, and the roller roughness is 0.4 μm. In the art, rough rolling is to gradually process the copper material from a thicker state to a size close to the required size through multiple passes. The main purpose of rough rolling is to significantly reduce the thickness of the material. Each pass may focus on significant thinning rather than the final surface finish or dimensional accuracy. The roughness of the roller will affect the surface quality of the material and the difficulty of subsequent processing. The relatively low roughness of the present invention (such as 0.4 μm) helps to reduce damage to the surface of the material, such as scratches and cracks, and can also help control the flow behavior of the material during rolling to ensure more uniform deformation.

[0047] Further, in step S4, the parameters of the secondary heating treatment are as follows: temperature is 550-800°C, and time is 3-5h. The secondary heating treatment of the present invention is carried out in a bell-type furnace, mainly because the bell-type furnace can provide a uniform temperature environment and good sealing, which is suitable for a precisely controlled heat treatment process, and is particularly suitable for the treatment of copper materials with high requirements for temperature uniformity and atmosphere control. During the treatment process, by adjusting the atmosphere in the furnace (such as using protective gases such as nitrogen and hydrogen to avoid oxidation), the copper material can be further protected to ensure its performance and surface quality. The present invention adopts the above-mentioned temperature and time, which can fully homogenize its internal structure and evenly eliminate internal stress. The above-mentioned insulation time also helps to ensure that the heat treatment effect of each part of the material is consistent.

[0048] Further, in step S5, the parameters of the intermediate rolling treatment are as follows: a total of 5 passes, and the total deformation of the passes is 75-85%, and the roughness of the roller is 0.2μm. The present invention performs intermediate rolling treatment after rough rolling treatment, the purpose of which is to further reduce the thickness and improve the dimensional accuracy and surface quality of the material on the basis of the substantial thinning of the material by rough rolling. The selection of 5 intermediate rolling treatments indicates that the degree of deformation of each pass is relatively small, and more attention is paid to the uniform deformation of the material and the improvement of the surface finish. The total deformation is 75-85%, which not only ensures the effective processing of the material, but also avoids excessive work hardening, which is beneficial to the subsequent finishing process. Compared with rough rolling, the roughness of the roller used in the intermediate rolling stage is significantly reduced, which is to obtain better surface finish while thinning the material. The roughness level of 0.2μm indicates that there are high requirements for surface quality, which helps to reduce material surface defects such as scratches and unevenness, and lays a good foundation for possible subsequent finishing or direct application.

[0049] Further, in step S5, an annealing treatment is performed in an air cushion furnace, and the parameters of the annealing treatment are as follows: temperature is 650-700°C, and time is 15-25s. The present invention adopts the above annealing temperature, which can effectively eliminate the work hardening inside the material, restore its good plasticity and conductivity, and at this temperature, the copper grains can be recovered and recrystallized, and its microstructure can be improved. In addition, the present invention adopts rapid annealing treatment (15-25s), which has the advantage of reducing the residence time of the material at high temperature, thereby reducing energy consumption, preventing or reducing possible excessive growth of grains, and maintaining a good surface state of the material, reducing oxidation risks.

[0050] Further, in step S5, the parameters of the finishing rolling process are as follows: a total of 2 passes, and the total deformation of the passes is 15-25%, and the roller roughness is 0.1μm. The present invention adopts 2 passes of finishing rolling treatment, which can accurately control the final specifications of the product through limited deformation while ensuring the material properties, and further limits the total deformation of the passes to 15-25%, which can effectively control the microstructure and performance of the material, and ensure sufficient plasticity to adapt to subsequent forming or use, and the use of a roller roughness of 0.1μm can ensure that the surface of the copper material is almost not damaged during the rolling process, and obtain a mirror-like high finish.

[0051] Further, in step S5, the secondary annealing treatment is carried out in a bell furnace, and the parameters of the secondary annealing treatment are as follows: the temperature is 230-260°C, and the time is 10-15h. The present invention adopts the secondary annealing treatment within the above temperature range. At such a temperature, the material can experience sufficient stress release and slight grain adjustment without causing obvious grain growth, which is very important for maintaining good physical and electrical properties of the material. The present invention adopts a relatively long holding time, which helps to ensure that the temperature inside the material is uniform, so that all parts can fully experience the annealing process, completely eliminate the internal stress generated during the processing, and at the same time, the microstructure of the material is fully recovered and recrystallized, thereby achieving the best comprehensive performance.

[0052] Furthermore, in step S6, the parameters of the heating and heat preservation treatment are as follows: temperature is 1000-1050°C, and time is 20-50min. The present invention adopts the heating and heat preservation treatment of the above temperature and time, which can deeply adjust the microstructure and performance of the copper material to ensure that it meets the application requirements of graphene.

[0053] The technical effects of the present invention are described below in conjunction with specific embodiments.

[0054] Example 1

[0055] The present embodiment provides a rolled copper foil for graphene. The rolled copper foil for graphene includes the following components in percentage by mass: O content 0.0001%, Cu content 99.99%, and the remainder is unavoidable impurities. The rolled copper foil for graphene in the present embodiment is prepared by the following preparation method:

[0056] S1. Weigh high-purity electrolytic copper as a raw material, and bake and heat the raw material at a temperature of 150° C. for 10 minutes to obtain a dry, water-free, and oil-free molten casting material;

[0057] S2, smelting the molten casting material obtained in step S1 at 1200° C., covering it with charcoal and letting it stand after smelting, placing it in a holding furnace after standing, covering it with flake graphite, and then casting it vertically and continuously at 1180° C. to obtain a rolled copper foil ingot;

[0058] S3, subjecting the rolled copper foil ingot obtained in step S2 to a primary heating treatment and a hot rolling treatment in sequence to obtain a hot-rolled strip; wherein the primary heating treatment is carried out in a walking beam furnace, and the parameters of the heating treatment are as follows: the temperature is 920° C., the atmosphere is a reducing atmosphere, and the air-fuel ratio of the reducing atmosphere is 0.92; the parameters of the hot rolling treatment are as follows: a total of 7 passes, and the deformation amount of the 5th pass is 35%;

[0059] S4, subjecting the hot-rolled strip obtained in step S3 to milling treatment and rough rolling treatment in sequence, and then placing it in a bell-type furnace for secondary heating treatment to obtain a rough-rolled strip; the parameters of the rough rolling treatment are as follows: a total of 7 passes, and the roll roughness is 0.4 μm; the parameters of the secondary heating treatment are as follows: the temperature is 550° C., and the time is 3 h;

[0060] S5, the rough rolling strip obtained in step S4 is subjected to intermediate rolling treatment, primary annealing treatment, finishing rolling treatment and secondary annealing treatment in sequence, and then placed in a bell furnace for three annealing treatments to obtain a finished rolled copper foil; wherein the parameters of the intermediate rolling treatment are as follows: a total of 5 passes, and the total deformation of the passes is 75%, and the roller roughness is 0.2 μm; the primary annealing treatment is carried out in an air cushion furnace, and the parameters of the primary annealing treatment are as follows: the temperature is 650° C., and the time is 15 s; the parameters of the finishing rolling treatment are as follows: a total of 2 passes, and the total deformation of the passes is 15%, and the roller roughness is 0.1 μm; the secondary annealing treatment is carried out in a bell furnace, and the parameters of the secondary annealing treatment are as follows: the temperature is 230° C., and the time is 10 h;

[0061] S6. The finished rolled copper foil obtained in step S5 is subjected to a heating and heat preservation treatment at 1000° C. for 20 minutes to obtain a rolled copper foil for graphene.

[0062] Example 2

[0063] The present embodiment provides a rolled copper foil for graphene. The rolled copper foil for graphene includes the following components in percentage by mass: O content 0.0004%, Cu content 99.992%, and the remainder is unavoidable impurities. The rolled copper foil for graphene in the present embodiment is prepared by the following preparation method:

[0064] S1. Weigh high-purity electrolytic copper as a raw material, and bake and heat the raw material at a temperature of 180° C. for 12 minutes to obtain a dry, water-free, and oil-free molten casting material;

[0065] S2, smelting the molten material obtained in step S1 at 1210° C., covering it with charcoal and letting it stand after smelting, placing it in a holding furnace after standing, covering it with flake graphite, and then casting it vertically at 1190° C. to obtain a rolled copper foil ingot;

[0066] S3, subjecting the rolled copper foil ingot obtained in step S2 to a primary heating treatment and a hot rolling treatment in sequence to obtain a hot-rolled strip; wherein the primary heating treatment is carried out in a walking beam furnace, and the parameters of the heating treatment are as follows: the temperature is 930° C., the atmosphere is a reducing atmosphere, and the air-fuel ratio of the reducing atmosphere is 0.94; the parameters of the hot rolling treatment are as follows: a total of 7 passes, and the deformation amount of the 5th pass is 36%;

[0067] S4, subjecting the hot-rolled strip obtained in step S3 to milling treatment and rough rolling treatment in sequence, and then placing it in a bell-type furnace for secondary heating treatment to obtain a rough-rolled strip; the parameters of the rough rolling treatment are as follows: a total of 7 passes, and the roll roughness is 0.4 μm; the parameters of the secondary heating treatment are as follows: the temperature is 650° C., and the time is 3.5 h;

[0068] S5, the rough rolling strip obtained in step S4 is subjected to intermediate rolling treatment, primary annealing treatment, finishing rolling treatment and secondary annealing treatment in sequence, and then placed in a bell furnace for three annealing treatments to obtain a finished rolled copper foil; wherein the parameters of the intermediate rolling treatment are as follows: a total of 5 passes, and the total deformation of the passes is 77%, and the roller roughness is 0.2 μm; the primary annealing treatment is carried out in an air cushion furnace, and the parameters of the primary annealing treatment are as follows: the temperature is 660° C., and the time is 18 s; the parameters of the finishing rolling treatment are as follows: a total of 2 passes, and the total deformation of the passes is 18%, and the roller roughness is 0.1 μm; the secondary annealing treatment is carried out in a bell furnace, and the parameters of the secondary annealing treatment are as follows: the temperature is 240° C., and the time is 12 h;

[0069] S6. The finished rolled copper foil obtained in step S5 is subjected to a heating and heat preservation treatment at 1010° C. for 30 minutes to obtain a rolled copper foil for graphene.

[0070] Example 3

[0071] The present embodiment provides a rolled copper foil for graphene. The rolled copper foil for graphene includes the following components in percentage by mass: 0.0007% O, 99.994% Cu, and the remainder is unavoidable impurities. The rolled copper foil for graphene in the present embodiment is prepared by the following preparation method:

[0072] S1. Weigh high-purity electrolytic copper as a raw material, and bake and heat the raw material at a temperature of 185° C. for 13 minutes to obtain a dry, water-free, and oil-free molten casting material;

[0073] S2, smelting the molten casting material obtained in step S1 at 1225° C., covering it with charcoal and letting it stand after smelting, placing it in a holding furnace after standing, covering it with flake graphite, and then casting it vertically and continuously at 1200° C. to obtain a rolled copper foil ingot;

[0074] S3, subjecting the rolled copper foil ingot obtained in step S2 to a primary heating treatment and a hot rolling treatment in sequence to obtain a hot-rolled strip; wherein the primary heating treatment is carried out in a walking beam furnace, and the parameters of the heating treatment are as follows: the temperature is 935° C., the atmosphere is a reducing atmosphere, and the air-fuel ratio of the reducing atmosphere is 0.95; the parameters of the hot rolling treatment are as follows: a total of 7 passes, and the deformation amount of the 5th pass is 37%;

[0075] S4, subjecting the hot-rolled strip obtained in step S3 to milling treatment and rough rolling treatment in sequence, and then placing it in a bell-type furnace for secondary heating treatment to obtain a rough-rolled strip; the parameters of the rough rolling treatment are as follows: a total of 7 passes, and the roll roughness is 0.4 μm; the parameters of the secondary heating treatment are as follows: the temperature is 700° C., and the time is 4 hours;

[0076] S5, the rough rolling strip obtained in step S4 is subjected to intermediate rolling treatment, primary annealing treatment, finishing rolling treatment and secondary annealing treatment in sequence, and then placed in a bell furnace for three annealing treatments to obtain a finished rolled copper foil; wherein the parameters of the intermediate rolling treatment are as follows: a total of 5 passes, and the total deformation of the passes is 80%, and the roller roughness is 0.2 μm; the primary annealing treatment is carried out in an air cushion furnace, and the parameters of the primary annealing treatment are as follows: the temperature is 680° C., and the time is 20 s; the parameters of the finishing rolling treatment are as follows: a total of 2 passes, and the total deformation of the passes is 20%, and the roller roughness is 0.1 μm; the secondary annealing treatment is carried out in a bell furnace, and the parameters of the secondary annealing treatment are as follows: the temperature is 245° C., and the time is 13 h;

[0077] S6. The finished rolled copper foil obtained in step S5 is subjected to a heating and heat preservation treatment at 1025° C. for 45 minutes to obtain a rolled copper foil for graphene.

[0078] Example 4

[0079] The present embodiment provides a rolled copper foil for graphene. The rolled copper foil for graphene includes the following components in percentage by mass: O content 0.0009%, Cu content 99.995%, and the remainder is unavoidable impurities. The rolled copper foil for graphene in the present embodiment is prepared by the following preparation method:

[0080] S1. Weigh high-purity electrolytic copper as a raw material, and bake and heat the raw material at a temperature of 220° C. for 15 minutes to obtain a dry, water-free, and oil-free molten casting material;

[0081] S2, smelting the molten material obtained in step S1 at 1250° C., covering it with charcoal and letting it stand after smelting, placing it in a holding furnace after standing, covering it with flake graphite, and then casting it vertically and continuously at 1220° C. to obtain a rolled copper foil ingot;

[0082] S3, subjecting the rolled copper foil ingot obtained in step S2 to a primary heating treatment and a hot rolling treatment in sequence to obtain a hot-rolled strip; wherein the primary heating treatment is carried out in a walking beam furnace, and the parameters of the heating treatment are as follows: the temperature is 950° C., the atmosphere is a reducing atmosphere, and the air-fuel ratio of the reducing atmosphere is 0.98; the parameters of the hot rolling treatment are as follows: a total of 7 passes, and the deformation amount of the 5th pass is 38%;

[0083] S4, subjecting the hot-rolled strip obtained in step S3 to milling treatment and rough rolling treatment in sequence, and then placing it in a bell-type furnace for secondary heating treatment to obtain a rough-rolled strip; the parameters of the rough rolling treatment are as follows: a total of 7 passes, and the roll roughness is 0.4 μm; the parameters of the secondary heating treatment are as follows: the temperature is 800° C., and the time is 5 h;

[0084] S5, the rough rolling strip obtained in step S4 is subjected to intermediate rolling treatment, primary annealing treatment, finishing rolling treatment and secondary annealing treatment in sequence, and then placed in a bell furnace for three annealing treatments to obtain a finished rolled copper foil; wherein the parameters of the intermediate rolling treatment are as follows: a total of 5 passes, and the total deformation of the passes is 85%, and the roller roughness is 0.2 μm; the primary annealing treatment is carried out in an air cushion furnace, and the parameters of the primary annealing treatment are as follows: the temperature is 700° C., and the time is 25 s; the parameters of the finishing rolling treatment are as follows: a total of 2 passes, and the total deformation of the passes is 25%, and the roller roughness is 0.1 μm; the secondary annealing treatment is carried out in a bell furnace, and the parameters of the secondary annealing treatment are as follows: the temperature is 260° C., and the time is 15 h;

[0085] S6. The finished rolled copper foil obtained in step S5 is subjected to a heating and heat preservation treatment at 1050° C. for 50 min to obtain a rolled copper foil for graphene.

[0086] Comparative Example 1

[0087] This comparative example provides a rolled copper foil for graphene, which is different from Example 1 only in that the rolled copper foil for graphene in this comparative example includes the following components in mass percentage: O content 0.001%, Cu content 99.99%, and the remainder being unavoidable impurities. The preparation method is the same as Example 1 and will not be repeated here.

[0088] Comparative Example 2

[0089] This comparative example provides a rolled copper foil for graphene, which is different from Example 1 only in that the rolled copper foil for graphene in this comparative example does not go through step S1 during the preparation process, and the rest is the same as Example 1, which will not be repeated here.

[0090] Comparative Example 3

[0091] This comparative example provides a rolled copper foil for graphene, which is different from Example 1 only in that step S2 of the preparation process of the rolled copper foil for graphene in this comparative example is as follows: the molten casting material obtained in step S1 is smelted at 1200°C, placed in a holding furnace after complete smelting, covered with flake graphite, and then subjected to a vertical full continuous casting method at 1180°C to obtain a rolled copper foil ingot; other steps and parameters are the same as those in Example 1 and will not be repeated here.

[0092] Comparative Example 4

[0093] This comparative example provides a rolled copper foil for graphene, which is different from Example 1 only in that, in step S3 of the preparation process of the rolled copper foil for graphene in this comparative example, a heating treatment is performed in air, and other steps and parameters are the same as those in Example 1, which will not be repeated here.

[0094] Comparative Example 5

[0095] This comparative example provides a rolled copper foil for graphene, which differs from Example 1 only in that the parameters of the hot rolling treatment in step S3 of the rolled copper foil for graphene in this comparative example are as follows: a total of 7 passes, and the deformation amount of the 5th pass is 33%; the other steps and parameters are the same as those in Example 1 and will not be repeated here.

[0096] Comparative Example 6

[0097] This comparative example provides a rolled copper foil for graphene, which differs from Example 1 only in that the parameters of the hot rolling treatment in step S3 of the rolled copper foil for graphene in this comparative example are as follows: a total of 7 passes, and the deformation amount of the 5th pass is 40%; the other steps and parameters are the same as those in Example 1 and will not be repeated here.

[0098] Comparative Example 7

[0099] This comparative example provides a rolled copper foil for graphene, which differs from Example 1 only in that the parameters of the intermediate rolling treatment in step S5 of the rolled copper foil for graphene in this comparative example are as follows: a total of 5 passes, and the total deformation of each pass is 73%; the other steps and parameters are the same as those in Example 1 and will not be repeated here.

[0100] Comparative Example 8

[0101] This comparative example provides a rolled copper foil for graphene, which differs from Example 1 only in that the parameters of the intermediate rolling treatment in step S5 of the rolled copper foil for graphene in this comparative example are as follows: a total of 5 passes, and the total deformation of each pass is 80%; the other steps and parameters are the same as those in Example 1 and will not be repeated here.

[0102] Comparative Example 9

[0103] This comparative example provides a rolled copper foil for graphene, which is different from Example 1 only in that the annealing time of the rolled copper foil for graphene in step S5 of this comparative example is 30s; the other steps and parameters are the same as those in Example 1 and will not be repeated here.

[0104] The properties of the rolled copper foils for graphene prepared in Examples 1-4 and Comparative Examples 1-9 of the present invention were tested, and the test results were as follows: Figure 1 , as shown in Table 1 and Table 2:

[0105] Figure 1This is the organizational diagram of the rolled copper foil for graphene prepared in Example 1 of the present invention, Figure 1 It can be seen that the rolled copper foil for graphene prepared by the element composition and preparation method of the present invention has a uniform internal structure and a large grain size.

[0106] Table 1: Performance test results of graphene rolled copper foils obtained in Examples 1-4 and Comparative Examples 1-9 (I)

[0107]

[0108]

[0109] Table 2: Performance test results of graphene rolled copper foils obtained in Examples 1-4 and Comparative Examples 1-9 (II)

[0110] Logo tensile strength Elongation Vickers hardness (HV) Flatness (≤2mm / 1000m) Example 1 265 45 142 0.4 Example 2 266 44 140 0.5 Example 3 258 46 141 0.6 Example 4 270 43 143 0.4 Comparative Example 1 245 38 127 1.2 Comparative Example 2 250 32 131 0.8 Comparative Example 3 251 38 135 0.7 Comparative Example 4 245 36 139 0.7 Comparative Example 5 243 36 127 0.9 Comparative Example 6 277 37 150 2.5 Comparative Example 7 241 33 125 1.0 Comparative Example 8 270 35 148 2.2 Comparative Example 9 259 42 137 0.6

[0111] It can be seen from the above data results that the technical solution reduces the influence of defects caused by impurities on the surface of copper foil by selecting and processing raw materials, and reduces the influence of excessively high or low temperatures on the quality of copper foil ingots by controlling the temperature during smelting and casting. The probability of surface defects at each stage is reduced by the coordinated control of heating atmosphere, hot rolling, annealing and cold rolling, and the surface roughness of the rolled copper foil is reduced to obtain a rolled copper foil with a larger grain size, thereby achieving the purpose of coordinated control of low surface roughness, low defect rate and larger grain size. Specifically, referring to Example 1 and Comparative Example 1, the performance test results show that when the oxygen content is increased so that it is not within the scope of the technical solution, the performance of the graphene rolled copper foil is affected. The reasons are as follows: when the oxygen content exceeds the threshold, the brittleness of the copper material will increase, affecting its processing performance and reliability. At the same time, the behavior of copper during the heat treatment process may change, such as the formation of oxides may affect the thermal stability and thermal conductivity of the material.

[0112] Further, referring to Comparative Example 2 and Example 1, it can be further seen that the baking and heating pretreatment has an impact on the technical solution. Considering that the water and oil on the surface are not completely removed, internal defects are generated in the subsequent preparation process. It can be seen that in the copper foil preparation process, pretreatment also has an important effect on performance. Comparative Example 3 does not use charcoal covering and standing steps. It can also be seen from the performance test results of Example 1 that the performance of the graphene rolled copper foil is also relatively reduced. The reason may be that the standing process helps to evenly distribute the temperature and further float and separate the impurities, and further remove the oxides obtained by combining the oxygen element with the trace impurities. When the charcoal covering and standing steps are not performed, the efficiency of removing the impurities will be reduced, thereby affecting the performance of the graphene rolled copper foil finally obtained.

[0113] In Comparative Example 4, the heat treatment was carried out in the air. Compared with Example 1 in which the heat treatment was carried out in a reducing atmosphere and under the condition of an air-fuel ratio with a slightly excess fuel, the performance of the obtained graphene rolled copper foil was reduced. The reason is considered to be that the oxygen contained in the air reacted with the copper foil for oxidation, thereby causing further generation of impurities. It can be seen that in the preparation process of the copper foil, creating an oxygen-free environment is very beneficial to the protection of the copper material, avoiding oxidation and promoting the optimization of material properties.

[0114] From the comparison of Comparative Examples 5 to 8 with Example 1, it can be found that in the present technical solution, the deformation amount of each pass is a key process parameter and plays a decisive role in the entire preparation process. Although a larger deformation amount of each pass can promote the grain refinement of the material, increase the dislocation density, and thus improve the hardness and strength of the material, too large a deformation amount may also cause surface defects such as cracks or ripples. By comparing the data of Comparative Examples 6, 8 and Example 1, it can be seen that when the deformation amount is greater than the range of the present technical solution, the flatness cannot meet the process requirements, and the material is easily made too brittle and hard, affecting the subsequent forming and welding performance. The data of Comparative Examples 5, 7 and Example 1 show that when the deformation amount is too small, it means that the thickness reduction in each rolling process is not enough, which will limit the generation and movement of dislocations inside the material, which is not conducive to the formation of new grain boundaries. As a result, the grain structure may not be fully refined, thereby affecting the strength and hardness of the copper foil.

[0115] However, in Comparative Example 9, a longer annealing time was used, and various properties of the copper foil obtained were slightly reduced. This may be because the residence time of the material at high temperature was increased, which further increased the risk of oxidation. In addition, the extended annealing time and excessive grain growth would reduce the strength of the material.

[0116] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A rolled copper foil for graphene, characterized in that: Calculated by mass percentage, the rolled copper foil for graphene includes the following components in mass percentage: O content 0.0001-0.0009%, Cu content 99.99-99.995%, and the remainder is inevitable impurities.

2. The rolled copper foil for graphene according to claim 1, wherein The rolled copper foil for graphene has a thickness of 20-50 μm, an average grain size of 400-600 μm, and a surface roughness of 0.06-0.08 μm.

3. A method for preparing a rolled copper foil for graphene as claimed in claim 1 or 2, characterized in that: The preparation method specifically comprises the following steps: S1. Weigh high-purity electrolytic copper as raw material, and bake and heat the raw material to obtain a dry, water-free, and oil-free molten casting material; S2, smelting the molten casting material obtained in step S1, covering it with charcoal and letting it stand after smelting, placing it in a holding furnace after standing, covering it with flake graphite, and then obtaining a rolled copper foil ingot by a vertical full continuous casting method; S3, subjecting the rolled copper foil ingot obtained in step S2 to a heating treatment and a hot rolling treatment in sequence to obtain a hot-rolled strip; S4, subjecting the hot-rolled strip obtained in step S3 to milling treatment and rough rolling treatment in sequence, and then placing the hot-rolled strip in a bell-type furnace for secondary heating treatment to obtain a rough-rolled strip; S5, subjecting the rough-rolled strip obtained in step S4 to intermediate rolling, primary annealing, finishing rolling and secondary annealing in sequence, and then placing the strip in a bell furnace for three annealing treatments to obtain a finished rolled copper foil; S6. The finished rolled copper foil obtained in step S5 is subjected to heating and heat preservation treatment to obtain a rolled copper foil for graphene.

4. The method for preparing a rolled copper foil for graphene according to claim 3, wherein: In step S1, the parameters of the baking and heating treatment are as follows: temperature is 150-220° C., and time is 10-15 min.

5. The method for preparing a rolled copper foil for graphene according to claim 3, wherein: In step S2, the smelting temperature is 1200-1250°C, and the vertical full continuous casting temperature is 1180-1220°C.

6. The method for preparing a rolled copper foil for graphene according to claim 3, wherein: In step S3, a heating treatment is performed in a stepping furnace, and the parameters of the heating treatment are as follows: a temperature of 920-950° C., a reducing atmosphere, and an air-fuel ratio of the reducing atmosphere of 0.92-0.98; and / or, The parameters of the hot rolling process are as follows: 7 passes in total, and the deformation amount of the 5th pass is 35-38%.

7. The method for preparing a rolled copper foil for graphene according to claim 3, wherein: In step S4, the parameters of the rough rolling process are as follows: 7 passes in total, and the roll roughness is 0.4 μm; and / or, The parameters of the secondary heating treatment are as follows: temperature is 550-800°C and time is 3-5h.

8. The method for preparing a rolled copper foil for graphene according to claim 3, wherein: In step S5, the parameters of the intermediate rolling process are as follows: a total of 5 passes, with a total deformation of 75-85% per pass, and a roll roughness of 0.2 μm; and / or, The primary annealing treatment is carried out in an air cushion furnace, and the parameters of the primary annealing treatment are as follows: temperature is 650-700° C., and time is 15-25 seconds.

9. The method for preparing a rolled copper foil for graphene according to claim 3, wherein: In step S5, the parameters of the finishing rolling process are as follows: 2 passes in total, with a total deformation of 15-25% per pass, and a roller roughness of 0.1 μm; and / or, The secondary annealing treatment is carried out in a bell furnace, and the parameters of the secondary annealing treatment are as follows: temperature is 230-260° C., and time is 10-15 h.

10. The method for preparing a rolled copper foil for graphene according to claim 3, wherein: In step S6, the parameters of the heating and heat preservation treatment are as follows: temperature is 1000-1050° C., and time is 20-50 min.

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